Answer:
0.8914
Step-by-step explanation:
You want to find the z-values associated with the x-values:
z = (x -μ)/σ
z1 = (57 -90)/12 = -2.75
z2 = (105 -90)/12 = 1.25
Look up these values in a probability table and find the difference of the table values.
p(z < z1) ≈ 0.00298 . . . . from a table or calculator
p(z < z2) ≈ 0.89435 . . . . from a table or calculator
p(57 < x < 105) ≈ 0.89435 -0.00298 = 0.89137 ≈ 0.8914
